Crystallization of Lactose-Protein Solutions in the Presence of Flavonoids.

Lactose is commonly crystallized in the presence of whey proteins, forming co-crystals of lactose and proteins. This work hypothesized that flavonoids such as rutin or epigallocatechin-3-gallate (EGCG) could be incorporated into the lactose and protein co-crystal structure since flavonoids may interact with both lactose and proteins. The interactions between whey proteins and flavonoids were first studied. Then, lactose-protein solutions were crystallized with and without flavonoids, measuring the kinetic parameters of crystallization and characterizing the resulting crystals. The incorporation of flavonoids in lactose-protein co-crystals depended on the hydrophilic nature of flavonoids. The hydrophilic EGCG was scarcely enclosed in the crystal lattice of lactose and avoided the inclusion of whey proteins in the crystals. In contrast, the less water-soluble rutin interacted with whey proteins and lactose, leading to the formation of co-crystals containing lactose, protein, and a large concentration of rutin (3.468 ± 0.392 mg per 100 mg of crystals).

Lipase Assisted (S)-Ketoprofen Resolution from Commercially Available Racemic Mixture.

Ketoprofen is a commercially available drug sold as a racemic mixture that belongs to the family of non-steroidal anti-inflammatory drugs known as profens. It has been demonstrated (in vitro) that (S)-ketoprofen is around 160 times more potent than its enantiomer (R)-ketoprofen, while accumulation of (R)-ketoprofen can cause serious side effects, such as dyspepsia, gastrointestinal ulceration/bleeding, pain, salt and fluid retention, and hypertension. In this work, four commercially available lipases were systematically assessed. Parameters such as conversion, enantiomeric excess, and enantioselectivity were considered. Among them, and by evaluating lipase load, temperature, solvent, and alcohol, Candida rugosa lipase exhibited the best results in terms of enantioselectivity E = 185 ((S)-enantiopreference) with esterification conversions of c = 47% (out of 50%) and enantiomeric excess of 99%. The unreacted (R)-enantiomer was recovered by liquid-liquid extraction and racemized under basic media, which was recycled as starting material. Finally, the (S)-alkyl ketoprofen ester was successfully enzymatically hydrolyzed to the desired (S)-ketoprofen with c = 98.5% and 99% ee. This work demonstrated the benefit and efficiency of using Candida rugosa lipase to kinetically resolve racemic ketoprofen by an environmentally friendly protocol and with the recycling of the undesired (R)-ketoprofen.

Seasonal evidences of microplastics in environmental matrices of a tourist dominated urban estuary in Gulf of Mexico, Mexico.

The study evaluated the spatial and seasonal variations of microplastic abundances in water, sediments, and commercial fishes of a semi-urban tourist impacted estuary in the Gulf of Mexico, Mexico. The prevalence of microplastics (MPs) elucidated diffuse sources namely long-range transport, domestic, agricultural, fishing, industrial and recreational activities and the local climatic conditions. Seasonally, the mean abundances of MPs in both water and sediments were high during Nortes (strong winds) followed by the dry and rainy seasons. Overall, black and blue colored MPs dominated the region and all the recovered plastics were fibers. The commercial fishes (n = 187) contained 881 MPs in their gastrointestinal tracts, suggesting that the food web of the estuary is highly prone to microplastic contamination. SEM images of extracted plastic fibers presented surface morphologies that are impacted by physical strains. Further, the elemental characterization of fibers using EDX displayed significant peaks of Al, As, Cl, Cr, Cu, Pb, and Zn that were used as additives during the production of plastics. The main types of polymers included low-density polyethylene, polyester, polypropylene, polycarbonate, rayon, polyvinyl chloride, polyacrylonitrile, polyamide, nylon and polyethylene terephthalate. MP abundances demonstrated in this study elucidate that estuaries are a major conduit for land-derived plastics to the ocean and the results will aid in implementing remedial/clean up actions of the estuary for better conservation of the ecosystem.

Mutarotation and solubility of lactose as affected by carrageenans.

It has been reported that polysaccharides like carrageenan can change the crystallization of lactose. However, it is still unclear whether changes in lactose mutarotation, solubility, and super-solubility are involved in carrageenans' effect on lactose crystallization. It has been established that the conversion of α- to ß-lactose forms (mutarotation) in an aqueous solution has a significant impact on lactose crystallization. Similarly, lactose solubility changes lead to changes in the metastable zone (MZ), a region between the solubility and super-solubility of lactose. The width of this MZ determines the temperature drop necessary to induce lactose nucleation. This work aimed to study the effect of carrageenans on lactose mutarotation and solubility. For this purpose, lactose solutions were added with ι and κ- carrageenan at two concentrations: 50 and 100 mg L-1. Optical rotation measurements estimated the proportion of ß/α isomers in lactose solutions. Besides, solubility and super- solubility was determined to build the MZ. The presence of carrageenans changed both the time to reach the mutarotation balance and the proportion of ß/α isomers at mutarotation equilibrium. Carrageenans decreased the solubility of lactose in a range of temperatures between 10 and 60 °C and reduced the metastable zone width (MZW).

Simultaneous Sulfite Electrolysis and Hydrogen Production Using Ni Foam-Based Three-Dimensional Electrodes.

The electrochemical oxidation of sulfite ions offers encouraging advantages for large-scale hydrogen production, while sulfur dioxide emissions can be effectively used to obtain value-added byproducts. Herein, the performance and stability during sulfite electrolysis under alkaline conditions are evaluated. Nickel foam (NF) substrates were functionalized as the anode and cathode through electrochemical deposition of palladium and chemical oxidation to carry out the sulfite electro-oxidation and hydrogen evolution reactions, respectively. A combined analytical approach in which a robust electrochemical flow cell was coupled to different in situ and ex situ measurements was successfully implemented to monitor the activity and stability during electrolysis. Overall, satisfactory sulfite conversion and hydrogen production efficiencies (>90%) at 10 mA·cm-2 were mainly attributed to the use of NF in three-dimensional electrodes with a large surface area and enhanced mass transfer. Furthermore, stabilization processes associated with electrochemical dissolution and sulfur crossover through the membrane induced specific changes in the chemical and physical properties of the electrodes after electrolysis. This study demonstrates that NF-based electrocatalysts can be incorporated in an efficient electrochemical flow cell system for sulfite electrolysis and hydrogen production, with potential applications at a large scale.

Individual and combined effect of pH and whey proteins on lactose crystallization.

Lactose is recovered by crystallization from cheese whey that is a by-product of cheesemaking. The whey used for the recovery of lactose usually has a residual content of protein that alters the crystallization of lactose. In addition, the pH of whey may fluctuate depending on the cheese variety. However, there is little information on how the pH modifies the effect that whey proteins have on lactose crystallization. Accordingly, this work aimed to evaluate the individual and combined effect of whey proteins and pH on the kinetics of crystallization, the crystal size distribution and the crystallinity of lactose. The addition of whey proteins in lactose solutions (25% v/v) modified the process of lactose crystallization. However, the effect that whey proteins had on lactose crystallization heavily depended on the pH. The number of crystals per milliliter as well as the growth and size distribution of crystals was the most affected with the changes in pH (pHs of 7, 5.5 and 4) and the addition of whey proteins (0 and 0.63%). All the treatment produced mostly α-lactose monohydrated but some treatments also generated crystals of ß-lactose (pH 5.5, 0% of proteins). Amorphous lactose was observed mainly in lactose solutions adjusted at pH 7 and added with whey proteins. This particular treatment also incorporated the highest amount of protein into the lattice of lactose crystals. The results of this work highlight the importance of controlling the pH of lactose crystallization, especially if there is a presence of whey proteins.

Lipase catalyzed epoxidation of fatty acid methyl esters derived from unsaturated vegetable oils in absence of carboxylic acid.

Nowadays the industrial chemistry reactions rely on green technologies. Enzymes as lipases are increasing its use in diverse chemical processes. Epoxidized fatty acid methyl esters obtained from transesterification of vegetable oils have recently found applications as polymer plasticizer, agrochemical, cosmetics, pharmaceuticals and food additives. In this research article, grapeseed, avocado and olive oils naturally containing high percents of mono and poly unsaturations were used as starting materials for the production of unsaturated fatty acid methyl esters. The effect of lauric acid as an active oxygen carrier was studied on epoxidation reactions where unsaturated fatty acid methyl esters were converted to epoxy fatty acid methyl esters using immobilized Candida antarctica Lipase type B as catalyst and hydrogen peroxide as oxygen donor at mild temperature and pressure conditions. After this study it was confirmed by 1H NMR, 13C NMR and GC-MS that the addition of lauric acid to the enzymatic reaction is unnecessary to transform the alkenes in to epoxides. It was found that quantitative conversions were possible in despite of a carboxylic acid absence.

Chemoenzymatic Kinetic resolution of (R)-malathion in aqueous media.

BACKGROUND: Malathion (R,S)-diethyl-2-[(dimethoxyphosphorothioyl)sulfanyl]butanedioate is a chiral organophosphorus compound used widely as pesticide for suppression of harmful insects such as mosquitoes. It is well known that in biological systems (R)-malathion is the active enantiomer, therefore a sustainable approach could be the use of only the biologically active enantiomer. The resolution of the commercial racemic mixture to obtain the pure active enantiomer combined with a recycling of the undesired enantiomer through a racemization process could be an attractive alternative to reduce the environmental impact of this pesticide. Thus, this work evaluates the use of four commercially available lipases for enantioselective hydrolysis and separation of malathion enantiomers from the commercial racemic mixture. RESULTS: Several lipases were methodologically assessed, considering parameters such as enzyme concentration, temperature and reaction rates. Among them, Candida rugosa lipase exhibited the best performance, in terms of enantioselectivity, E = 185 (selective to the (S)-enantiomer). In this way, the desired unreacted (R)-enantiomer was recovered in a 49.42 % yield with an enantiomeric excess of 87 %. The monohydrolized (S)-enantiomer was recovered and racemized in basic media, followed by esterification to obtain the racemic malathion, which was recycled. In this way, an enantioenriched mixture of (R)-malathion was obtained with a conversion of 65.80 % considering the recycled (S)-enantiomer. CONCLUSION: This work demonstrated the feasibility of exploiting Candida rugosa lipase to kinetically resolve racemic malathion through an environmentally friendly recycling of the undesired (S)-enantiomer. Graphical AbstractLipase catalyzed enantioselective resolution of (R)-malathion in aqueous solvent.

Synthesis of a Functionalized Benzofuran as a Synthon for Salvianolic Acid C Analogues as Potential LDL Antioxidants.

A palladium mediated synthesis of a common synthon for the syntheses of antioxidant analogues of naturally occurring salvianolic acids is presented. The synthetic route may be used to obtain analogues with a balanced lipophilicity/hydrophilicity which may result in potentially interesting LDL antioxidants for the prevention of cardiovascular diseases.

Pyrene-fullerene C60 dyads as light-harvesting antennas.

A series of pyrene-fullerene C60 dyads bearing pyrene units (PyFC12, PyFPy, Py2FC12 and PyFN) were synthesized and characterized. Their optical properties were studied by absorption and fluorescence spectroscopies. Dyads were designed in this way because the pyrene moeities act as light-harvesting molecules and are able to produce "monomer" (PyFC12) or excimer emission (PyFPy, Py2FC12 and PyFN). The fluorescence spectra of the dyads exhibited a significant decrease in the amount of pyrene monomer and excimer emission, without the appearance of a new emission band due to fullerene C60. The pyrene fluorescence quenching was found to be almost quantitative, ranging between 96%-99% depending on the construct, which is an indication that energy transfer occurred from one of the excited pyrene species to the fullerene C60.